Hitch flex?

What have you found is the cause?

Thank you for your replies. You all confirm what I suspected.

Side wall has separated from horizontal frame structure.

The side wall sits down on top of horizontal frame and is bolted to it with lag screws. They pull loose or break.

Then when you hitch up pin box structure lifts side wall before it starts lifting horizontal frame.
When unhitch and landing gear carrying weight, side wall settles back down onto horizontal frame

Caulking is NOT going to work..will just continue to pull loose/gap

New lag bolts can be install thru side of horizontal frame into side wall bottom plate. Drill holes in a 'W' pattern. Use 1/2" X 2 1/2" lag screws.

Also add couple up thru bottom plate.


OR''

Side wall stud welds on bottom plate have broken.......then you need to remove side wall and re-weld

OR'''

Pin box structure has cracks/broken welds/torn metal..re-weld/add braces/supports


You will need to remove overhang panel and inspect frame structure.
Hitch-up and unhitch to locate issue.

Don't remember reading anything about Sunnybrooks having frame issues but the symptoms are not good! You need to open up the bulkhead area around the pinbox and have a look see! Good luck with this!

As newman fultimer said you probably have a break in the frame on that side. There should be no movement or gapping when you hitch up.

you have a broken frame it sounds like